简介:Patarinproposedthedragonscheme,pointedouttheinsecurityofthedragonalgorithmwithonehiddenmonomialandsuggestedacandidatedragonsignaturealgorithmwithacomplicatedfunction.Thispaperpresentsanalgebraicmethodtoattackthecandidatedragonsignaturealgorithm.TheattackborrowsthebasicideaoftheattackduetoKipnisandShamir,andutilizestheunderlyingalgebraicstructureofthecandidatedragonsignaturealgorithmovertheextensionfieldtoderiveawaytoenablethevariableYbeviewedasafixedvalue.Theattackrecoverstheprivatekeysefficientlywhentheparametersaren≤25andD=[logqd]≤3.
简介:环境变化被期望由决定幼苗建立和成功转移分发和许多植被。然而,很当前的生态系统模型仅仅在biogeophysics上集中于不能生活的因素的影响(例如,全球分发,等等),在人口动力学忽略他们的角色(例如,幼苗建立率,死亡率,等等)生态的社区。如此的疏忽可以在生态系统人口动力学导致偏爱(例如在为在森林生态系统的木质的种类的人口密度的变化)并且特征。在现在的学习,为作为功能而非阀值介绍土壤水的一个新建立计划被开发并且验证,用象一张测试床的版本1.0IAP-DGVM。结果证明在建立计划的土壤水在森林转变地区上有显著影响。与原来的计划相比,新计划显著地改进了树人口密度的模拟,特别在森林和转变地区的外部区域。因而,在森林里偏导部分范围在约78.8%全球格子房间被减少。在相对偏爱从34.3%~4.8%被减少的地方,树,灌木,草和赤裸的土壤的全球模仿的区域分别地更好表现了,从27.6%~13.1%,从55.2%~9.2%,并且从37.6%~3.6%。而且,新计划有更合理的相关性在吝啬的年度降水上种功能的类型(PFT),并且在亚马逊和中央非洲的热带雨林外设区域描述了正确主导的PFT。
简介:Inthispaper,asubdivisionschemewhichgeneralizesasurfaceschemeinpreviouspaperstovolumemeshesisdesigned.Theschemeexhibitssignificantcontrolovershrink-age/sizeofvolumetricmodels.Italsohastheabilitytoconvenientlyincorporateboundariesandcreasesintoasmoothlimitshapeofmodels.ThemethodpresentedhereismuchsimplerandeasierascomparedtoMacCrackenandJoy's.Thismethodmakesnorestrictionsonthelocaltopologyofmeshes.Particularly,itcanbeappliedwithoutanychangetomeshesofnonmanifoldtopology.
简介:Oneoftheopenissuesinprincipleschemedesignofmechanicalsystemsisprinciplerepresentation,whichnotonlyoutliesthephysicalprinciples,butalsofacilitatesthedesignsynthesis.Anenergy-basedapproachtorepresentprincipleschemedesignisproposed.Firstly,anenergyinteractionmodelofmechanicalsystemsisestablishedandanintermediatemodelisderived,inwhichprincipleschemedesignistransformedintosolvingtheenergyfunctionsofsystem.Thentheenergyfunctionsaremodeledwiththelanguageofbondgraphs,andprinciplerepresentationforcomponenytsispresented.Finally,characteristicsofthedevelopedrepresentationapproachareanalyzedandadesignexampleofgatedrivesystemisgiventodemonstratethisapproach.
简介:The’polarcoding’proposedbyDr.Arkancanachievethesymmetriccapacityofbinary-inputdiscretememorylesschannels(B-DMC).ThegeneratormatrixofpolarcodesisGN=BNFnforN=2n,BNwasapermutationmatrix.Inthearticleitwasrealizedwithaninterleaver,sothematrixproductionofGNwasavoided;thenthegeneratormatrixwasjustdeterminedbythematrixFnwhichwasconstructedwiththreesub-matrixesofFn-1andone2N-1orderzeromatrix,itwasdealwithfastHadamardtransform(FHT)algorithm.Thecomplexityofthenewschemewasreducedsharply,andaniterativealgorithmalsocanbeused.TheexampleshowedthatwhenN=8,complexityoftheencodingschemewasjust16whichisobviouslylessthanthatoforiginalencodingscheme36.
简介:ThisarticledescribesalocalerrorestimatorforGlimm'sschemeforhyperbolicsystemsofconservationlawsandusesittoreplacetheusualrandomchoiceinGlimm'sschemebyanoptimalchoice.Asaby-productofthelocalerrorestimator,theprocedureprovidesaglobalerrorestimatorthatisshownnumericallytobeaveryaccurateestimateoftheerrorinL1(R)foralltimes.Althoughthereispartialmathematicalevidencefortheerrorestimatorproposed,atthisstagetheerrorestimatormustbeconsideredad-hoc.Nonetheless,theerrorestimatorissimpletocompute,relativelyinexpensive,withoutadjustableparametersandatleastasaccurateasotherexistingerrorestimators.Numericalexperimentsin1-DforBurgers'equationandforEuler'ssystemareperformedtomeasuretheasymptoticaccuracyoftheresultingschemeandoftheerrorestimator.
简介:Inubiquitouscomputing,datashouldbeabletobeaccessedfromanylocation,andthecorrectnessofdatabecomesvitalduringthecommunication.Supposethatmanyuserssigndifferentmessagesrespectively,beforeforwardingorsendingthesemessages,thentheverifiermustspendalotofcomputingtimetoverifytheirsignatures.Consequently,theaggregatesignatureschemeisaneffectivemethodofimprovingefficiencyinthiskindofsystems,whichprovidestheconveniencefortheverifier.Inthispaper,weproposeanewcertificatelessaggregatesignatureschemewhichisefficientingeneratingasignatureandverification.ThisschemeisprovablysecureundertheextendedcomputationalDiffie-Hellmanassumption.
简介:Vehielesenlistedwitheomputing,sensingandcommunicatingdevicescancreatevehicularnetworks,asubsetofcooperativesystemsinheterogeneousenvironments,aimingatimprovingsafetyandentertainmentintraffic.Invehicularnetworks,avehicle’sidentityisassociatedtoitsowner’sidentityasauniquelinkage.Therefore,itisofimportancetoprotectprivacyofvehiclesfrombeingpossiblytracked.Obviously,theprivacyprotectionmustbescalablebecauseofthehighmobilityandlargepopulationofvehicles.Inthiswork,wetakeanon-trivialsteptowardsprotectingprivacyofvehicles.Asprivacydrawspublicconcerns,wefirstlypresentprivacyimplicationsofoperationalchallengesfromthepublicpolicyperspective.Additionally,weenvisionvehicularnetworksasgeographicallypartitionedsubnetworks(cells).Eachsubnetworkmaintainsalistofpseudonyms.Eachpseudonymincludesthecell’sgeographicidandarandomnumberashostid.Beforestartingcommunication,vehiclesneedtorequestapseudonymondemandfrompseudonymserver.Inordertoimproveutilizationofpseudonyms,weaddressastochasticmodelwithtime-varyingarrivalanddeparturerates.Ourmaincontributionincludes:1)proposingascalableandeffectivealgorithmtoprotectprivacy;2)providinganalyticalresultsofprobability,varianceandexpectednumberofrequestsonpseudonymservers.Theempiricalresultsconfirmtheaccuracyofouranalyticalpredictions.
简介:Theperformanceofmassivemultiple-inputmultiple-output(MIMO)systemislimitedbypilotcontamination.Toreducethepilotcontamination,uplinkanddownlinkprecodingalgorithmsareputforwardbasedoninterferencealignmentcriterion.Intheuplinkreceivingprocessing,thetargetfunctionalignsthepilotcontaminationandtheinterferencesignalstothesamenullspaceandacquiresthemaximalspacedegreeofthedesiredsignals.Theuplinkreceivingprecodingmatrixissolvedonmaximalsignaltointerferenceplusnoiseratio(SINR)criterionconsideringtheimpactofthepilotcontaminationonchannelestimations.Theuplinkreceivingprecodingmatrixisusedasthedownlinktransmittingprecodingmatrix.Exploitingthechannelreciprocity,itisprovedthat,iftheuplinkreceivingprecodingmatrixachievesmaximalSINR,theidenticalprecodingmatrixcanbeusedinthedownlinktransmissionandacquiresmaximalsignaltoleakageplusnoiseratio(SLNR).Simulationsshowthatthespectrumefficiencyoftheproposedalgorithmcanreachabout1.5timeshigherthanthatofpopularmatchedfiltering(MF)precodingalgorithm,andabout1.1timeshigherthanmulti-cellminimummeansquareerror(MMSE)precodingalgorithm.Theperformanceoftheproposedalgorithmcanbeimprovedapproximatelylinearlywiththeincreasingofthenumberofantennas.
简介:Quantumalgorithmsbringgreatchallengestoclassicalpublickeycryptosystems,whichmakescryptosystemsbasedonnon-commutativealgebraicsystemshoptopic.Thebraidgroups,whicharenon-commutative,haveattractedmuchattentionasanewplatformforconstructingquantumattack-resistantcryptosystems.Aringsignatureschemeisproposedbasedonthedifficultyoftherootextractionproblemoverbraidgroups,whichcanresistexistentialforgeryagainsttheadaptivelycho-sen-messageattackundertherandomoraclemodel.